Metal mold and method of casting



A. B. NORTON METAL MOLD AND METHOD OF CASTING Oct. 30, 1928.

Filed Feb. 25, 1924 4 Sheets-Sheet INVENTOR m A.

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A. B. NORTON ME AL MOLD AND METHOD 0F CASTING Oct. 30, 1928.

Filed Feb. 25, 1924 4 Shets-. she t i F I N Q M Qct SO, 1928. 1,689,595

A. B. NORTON METAL MOLD AND METHOD OF CASTING Filed Feb. 25, 1924 4Sheets-Sheet 3 FIG-5' FiGS INVENTOR ATTOR EYS Oct. 30, 1928. 1,689,595

r A. B. NORTON I XETAL MOLD AND QETHOD OF CASTING Filed Feb. 25, 1924 4shets-sheet 4 my. I F1011 INVENTOIRI ATT RNEY5 Patented Oct. 30, 1928. v

tJNIT-ED STATES PATENT OFFICE.

ALLEN B. NORTON, OF CLEVELAND, OHIO, ASSIGNOR TO ALUMINUM COMPANY OFAMERICA, 01 PITTSBURGH, PENNSYLVANIA, A CORIORATION OF PENNSYLVANIA.

METAL MOLD AND METHOD OF CASTING.

Application filed February'23, 1924. Serial No. 694,479.

This invention relates to the art of casting metallic articles inpermanent molds and in particular to a mold and a method tor castingrelatively large, thin walled, hollow articles. Although it isespecially applicable to aluminum alloys, the principles underlying theconstruction and operation of the mold and the steps of the method areapplicable to various other'metals and alloys,

notably light metals having melting po;ntS within a range of 150 degreescentigrade of pure aluminum, approximately.

Qne object of the invention is to construct a mold for castingrelatively large, thin walled articles having a gate and feeder cavityat one side of the casting cavity and means for bypassing molten metalfrom the casting cavity adjacent the feeder cavity into more remoteparts of the casting cavity. Another object of the invention is toconstruct a mold for casting relatively large, thin walled articleshavin a gating cavity or a gating and feedercavity from either or bothof which metal is bypassed through 5 feeders to a portion or portions ofthe casting remote from the first mentioned gating cavity or gating andfeeder cavity, the by- .passing consisting of a connecting cavity oit'greater thickness than the minimum section of the casting. A furtherobject is to construct a permanent mold for thin walled articles inwhich one or more passages are provided above the casting cavity andcommunicating therewith at separate points, the cross sectionaldimensions of the passages being greater than the thickness of theadjacent casting walls.

A still further object is to construct a new and improved permanent moldfor casting hollow articles of metals having melting points comparhbleto pure aluminum in which many improved features of construction willappear more in detail and be claimed here'nafter.

Another object is to provide a method of casting in a permanent molda-sound, thin walled, hollow, relatively large article co1n-,

' vent the ent-rapping of air in the molten metal and to preventagitation or splashing of the metal as it enters the mold, and leadingthe highly heated metal from the castmg cavity adjacent the gate intothe somewhat cooler but advancing metal in the casting cavity tocomplete the filling of the mold. Y

Another object is to provide a new and improved method of casting thinwalled articles composed of metal having'a melting point comparable toaluminum in permanent molds which comprises leading molten metalsmoothly and rapidly through a single gate into a casting cavity,causing part of the metal to flow toward remote. parts of the castingcavity and causing other parts of the metal while still highly heated toreunite with the metal in the remote parts of the cast'ng cavity andto'complete the filling of the cavity.

Other objects will appear, and will be pointed out hereinafter.

In the drawings accompanying this specification and forming apartthereof one form of device is shown embodying my invention and adaptedto carry out my new and improved process.

Figure 1 is a top plan view of an assembled mold constructed inaccordance with my invention.

Figure '2 is a longitudinal view taken on line 22 of Figure 1 partly incross section and showing certain of the mold members in side elevation.

Figure 3 is a vertca'l. cross sectional View taken on line 33 of Fig. 1.I

Figure 4 is an enlarged fragmentary detail view of certain of thestructures shown in Figure 3.

Figures 5 and 6 are respectively enlarged fragmentary cross sectionalviews taken on lines 5 5 and 66 respectively of Figure 3.

F igures'? and 8 are respectively side elevation and top plan views ofan article with the gate metal attached as cast in apparatus embodyingmy invention and by means of I my lmproved process.

Figures 9, 10, 11, 12, 13, lfl, and 15, respectively represent crosssectional views taken .on lines 99, 1010, 1111, l212, 13-13,

1414, and 1515 of the gate and feeders of Figure 7.

Figures 16 and 17 are respectively fragmentary cross sectional viewstaken on lines 16-16 and 17-47 of Figure 8, and

Ten

, Figure 18 is a perspective view of the casting shown in Figures 7 and8 but with certain of the risers broken away.

Referring more particularly to Figures 1 to 6 inclusive my improved formof mold comprises a base member 1 having atone end thereof a post 2secured in a vertical hole 3 in base'l by means of a nut 41 Pivotallymounted on post 2 are two pairs of mold members 5 and 6, the members 5being seated on the base 1 and adapted to slide thereon into and out ofabutting position while mold members 6 are seated on the top of members5 and adapted to move with or independently of members 5. Handles 7 areprovided on members 5 and 6 to facilitate movement of these membersabout the post 2. A pilot 8 is provided on the upper surface of base 1to assist in positioning the members 5 with respect to each other and toform the end wall of the casting cavity which in the case illustrated,is formed partly in the top of the base 1. A similar pilot 9 is likewiseformedon the top surface of members 5 to assist in positioning members6.

The meeting faces of mold members 5 and 6 are suitably recessdto form agate 10, a rise 11 communicating therewith and in turn communicatingwith a casting cavity 12.v

If desired, a feeder or riser cavity13 may be provided in communicationwith casting cavity 12 and opposite to feeder cavity 11. Means areprovided for withdrawing molten metal from the casting cavity 12 nearthe feeder cavity 11 and returning it to the casting cavity at pointsremote from the feeder cavity 11. Such cavities are preferably formed inthe faces of the mold member 6 above the casting cavity 12 asrepresented by numeral 14. The connections between these passages andthe casting cavity 12 being indicated at points numbered 15. It may bedesirable to provide additional riser cavities from these passages 14 asfor example those herein designated by 16.

A core 17 comprising a hollow shell seats upon the'top surface of member6 and extends downwardly into the casting cavity to form the inner endand side walls of the casting cavity. This core is preferably composedof two parts. The tubular portion 18 which is adapted to extend into thecasting cavity and form the inner end and side walls thereof is securedto a plate-like top 19 as by means of cap screws 20 which screw intobosses 21 of the part 18. The plate 19 is preferably somewhat largerthan the tubular part 18 so that it rests upon the top of members 6thereby supporting the core in the casting cavity The handle 22 securedto plate 19 of,core 17 serves as a means to remove the core from thecasting cavity. The tubular portion 18 of the core 17 has its side wallwhich lies opposite the gate 10 and feeder cavity 11 enlarged somewhatas at 23, so that a portion thereof may be cut away and an insert 24secured thereto as by cap screws-25. The purpose of providing the insert24 at this point, is to permit long continued use of the core byperiodically renewing the insert if the latter shows any tendency toitting or deterioration due to contact therewith of the first enteringmolten metal. This provision for the insert is, however, largelyprecautionary rather than necessary. a

To form a handle receiving bracket on the article to be cast forexample, consisting of two independent arms extending outwardly and thentoward each other as shown in Figure 8, I have provided twoco-operating' core pins 28 and 27. Core pin 26 is horizontally locatedin one of the mold members 5 being seated in a suitable recess thereinso that its top lies substantially flush with the top of the moldmember. A handle 28 serves to move the core pin back and. forth inthemold member 5. The innor end of this corepin is recessed on the 7 topsurface thereof as at 29 to conform with the lower end 30 of core pin 27and receives this. portion 30 when the core pins are in assembledposition preliminary to making a casting. Gore pin 27 comprises anenlarged outer end portion 31 adapted in certain positions of the pin torest upon the topsurface of mold member 6; a shank 32 and an enlargedlower end 30. The configuration of the shank 32 and the end 30 will moreclearly of the tubular part 18 of the core which lies opposite the corepin 27 and may secure such an insert in the position by such means as ascrew 35 and dowel pin 36. Although I have previously mentioned recesses14 as being formed in the inner faces of mold members 6, I find itadvisable to form the part of such recesses lying opposite the core pin27in the core itself and accordingly has so shown these recesses inFigures 3 and 4 where a portion of recess 14 is formed in the insert 34.

In operating the -mold herein described the mold members 5 and 6 arebrought into the assembled position shown in Figure .1 and the core islowered into place in the casting cavity. Core pin 27 is-raised to theposition 'shown in Figure 3 and core pin 26 is then insertedtherebeneath as also shown Inn in this figure. After the molten metalhas been poured into the gate 10 and has filled and solidified in thecasting cavity in the various passages, riser or feeder and gatecavities the core pin 26 is withdrawn to approximately the positionshown in Figure 4. Core pin 27 is then pushed downwardly until the endportion 30 thereof clears the handle bracket on the casting or until theouter end portion 31 of the pm seats on the top of mold member 6. Thecore 17 is then elevated out of the casting cavity and finally the moldmembers 5 and 6 are swung horizontally about the vertical pivot post 2and the casting is ready to be rempved from the mold. The core pin 27 isseated in a suitably shaped recess in mold member 6 and moves therewith,when the latter is moved. To remove the core pin 27 from the handlebracket on the casting the shank 32 of the pin has been offset from thevertical center line of the pin an amount sufficient to permit the shank32 to pass through the space between the separate armsof the handlebracket as the mold member 6 is turned about the pivot post 2. Theupwardly converging side surfaces on head 33 of, pin 27 can be readilyseparated from the adjacent casting without injury thereto. The mold isthen ready to be reassembled preliminary to the making of anothercasting.

In Figures 7 to 16 inclusive I have shown 1 a casting which may be madein the mold disclosed in Figures 1 to 6 inclusive, this articleembodying certain features of my invention and cast by'my new andimproved method. In making relatively large thin walled cup-likecastings as shown in permanent molds it is often diflicult even when themolds are highly heated to cause the metal to flow into all parts of thecasting cavity and completely fill the same. This difliculty is perhapsmore pronounced with metals having a crystallization shrinkage andmelting point comparable to aluminum. Aluminum alloy and other lightmetals and alloy of melting points comparable to aluminum areparticularly difficult to cast into such described wall thicknesses andshapes. Furthermore these metals because of their lightness tend toocclude and retain air and other gases and thus render the cast ngsporous or pitted unless special precautions are observed to prevent the'entrappingof air or the entry of any entrapped air into the castingcavity. With the foregoing difficulties in mind, I have provided a gate10 which is designed to prevent the entry of entrapped air into thecasting cavity and at the same time to permit the rapid yet smooth andunagitated filling of the casting cavity with molten metal which gateper se, does not form a part of this particular invention but isdescribed and explained in a co-pending application, now Patent No.

1,553,628 issued September 15, 1925, and is I at its lower end with anenlarged upright feeder cavity 11 adjacent to and in communication withthe casting cavity through a short narrow passage extending throughoutsubstantially the entire height of the casting cavity, the function ofthis feeder cavity being to provide a relatively large supply of highlyheated molten metal adjacent to the casting cavity to serve as areservoir in filling up voids in the casting due to the shrinkage of themetal therein as it cools and thereby to insure complete filling of thecavity and substantially elimination of any cracks or voids due tocrystallization shrinkage of the metal in the casting cavity. Inrelatively large castings such as are herein disclosed, I have found itpreferable to employ an enlarged feeder cavity 13 substantially oppositeto the gate 10 and feeder cavity 11. This feeder or riser 13 alsocommunicates through a short narrow passage with the casting cavity andacts in substantially the same manner as does the feeder cavity 11.

A novel and important feature of my a present invention is the provisionof means for withdrawing molten metal from the casting cavity near oradjacent to its point of entry from the feeder cavityvll and gate 10into the casting cavity and conducting the still highly heated moltenmetal into parts of the casting cavity remote from the feeder cavity 11and in leading this still highly heated molten metal into the forwardpart of the metal advancing in the casting cavity so that the lattermetal is restored approximately to its former temperature or so that thetemperature of the metal is elevated suificiently to insure travel ofthe molten metal to all parts of the casting cavity and complete fillingthereof before solidification takes place. Although withdrawing andreintroducing the molten metal just described may be carried out byvarious means, I. have found that it may conveniently be done by meansof the passages 14 and 15; In relatively large articles such as areherein disclosed I have found it preferable to employ passages 14 and 15on opposite sides of the casting cavity as shown in Figure 3.

My improved method as practiced on the casting shown herein will beunderstood by reference to these figures and particularly to Figure 18.The molten metal introduced into the gate passage 10 flows downwardlytherethrough into the feeder cavity 11 and thence into the castingcavity 12. As. the

pouring proceeds rapidly the gatelO and riser 11 become filled and themetal in the casting cavity flows toward the remote parts thereof andinto the feeder or riser -13.

Since the side walls of the casting cavity are relatively thinthe metaltends to cool quickly and to flow sluggishly thereby causing the"casting cavit adj acent to feeder cavity 11 to become fille to its topwhile the remote parts of casting cavity are being filled. The head ofhighl heated molten metal in the gate 10 and coder 11 causes the metalin the casting cavity 12 to rise through the openings or passages15-adjacent the feeder cavity 11 and flow through passages 14 toward theremote parts of the casting cavity and to flow into the casting cavitythrough the other openings or passages 15 while still highly heated. Theenlarged passages 14 and the risers 16 thereabove have a capacity for asubstantial quantity of molten metal and the cooling rate thereof iscorresponr ingly decreased so that the metal which reenters the castingcavity is more highly heated than the metal in the thin parts of thecasting cavity. The reentry of this highly heated molten metal and amixture thereof with the advancing portion or forward part of the metalflowing in the cast ing cavity tends to increase the temperature of thelatter or at least to maintain it at the temperature necessary forsatisfactory flowing of the metal in the casting cavity and the completefilling thereof. After the casting cavity has been completely filled therisers 16 may and probably do assist in com pensating for anycrystallization shrinkage occurring in the casting itself.

It will thus be seen that by withdrawing highly heated molten metal fromthe casting cavity near its point of entry there into and thenreintroducing such metal while still highly heated into the castingcavity at points remote from the gate, I am able to completely fill thecasting cavity for relatively large thin walled castings even though themetal has a relatively high melting point as compared with tin and arelatively high crystallization shrinkage as compared with iron, as anexample of both of which I may mention aluminum alloy.

7 For the purpose of further assisting those skilled in the art topractice my inventidn, I have shown in Figures 7 to 18 inclusive variousviews and cross sections of the sizeand shape of cavities which Ihavefound satisfactory in making castings of the class described and inpracticing my improved process. For example, Figures 9, 1p, 11, 12 and13 illustrate cross sectional dimensions of the gate: Figures 14 and 15represent corresponding dimensions of the feeders 11 and 13 and Figures16 and 17 show the relative size of the casting cavity and passage 14.In Figures 7, 8, 16, 17 and 18, 10 represents the gate metal of acasting, 11 the riser metal formed in riser cavity 11, 12 the castingform in the casting cavity 12, 13 the metal solidifying in the riser orfeeder 13 connects each of the portions thereof immediately beneath therisers 16 is somewhat" smaller in cross sections than these laterportions. Although these passages could be enlarged if desired they areas shown considerably larger in cross sectional dimensions than theadjacent sections of the casting and have been found entirelysatisfactory for the desired purpose.

Having thus described my invention, what I desire to secure by LettersPatent .is defined and what is claimed it being understood that variouschanges in the structure herein shown may be made by those skilled inthe art without departing from the scope of my invention and furtherthat the steps of my method may be altered, varied or changed somewhatalso without departing from the scope of my invention.

WVhat I claim is:

1. The new and improved method of casting a thin walled hollowarticleccomposed of a metal having a melting point comparable to that ofpure aluminum in a permanent mold Which comprises introducing the moltenalloy into a suitable casting cavity through a gate at one side thereof,permitting part of the metal to flow in the cast-' ing cavity toward theparts thereof remote from the gate, and withdrawing molten metal fromadjacent the gate and leading it into the casting cavity at a pointremote from the gate. 7

2. The new and improved method of casting a thin walled, hollow aluminumbase alloy article in a permanent mold comprising feeding metal smoothlyand rapidly into a suitable casting cavity at one side thereof,permitting part of the metal to flow in the casting cavity toward remoteparts thereof, and withdrawing highly heated molten metal from adjacentto the point of entry of such metal into the casting cavity, and addingit to the metal flowing in the casting cavity as the latter metal coolsto complete the filling of the mold.

3. The new and improved method of cast-- ing thin walled, cup shapedaluminum base alloy articles in a permanent mold comprising feedingmolten alloy into the casting cavity at one side thereof, permitting themetal to advance in the casting cavity toward remote arts thereof andmaintaining in a highly fieated condition the forward part of theadvancing met-a1 until the casting cavity is completely filled.

4. The new and improved method of casting relatively large thin walledcup shaped articles composed of aluminum base alloy in a permanent moldcom rising leading highly heated molten alloy mto one side mote parts ofthe casting cavity and at intcrvals uniting the forward parts of each ofthe said separate streams.

5. The new and improved method of casting relatively large thin walledcup shaped articles composed of aluminum base alloy in a permanent moldcomprising leading molten alloy into the casting cavity at one sidethereof, permitting the alloy to advance toward remote parts of thecavity in separate streams of different cross sectional. dimensions andat intervals reuniting the flowing metal of the two streams. K

6. The new and improved method of casting relatively large thin walledcup shaped articles composed of aluminum base alloy in a permanent moldcomprising introducing molten metal into one side of a casting' cavity,permitting the metal to advance toward remote parts of the cavitythrough separate passages and uniting the advancing metal in theseparate passages at intervals.

ing relatively large thin walled cup shaped articles composed ofaluminum 'base alloy in a permanent mold comprising introducing moltenmetal into a casting cavity, permitting t-he metal to advance towardremote parts of the cavity and .maintaining substantially constant thetemperature of the forward position. of the advancing metal in thecasting cavit by adding directly thereto molten metal ta en from thecasting cavity adjacent to its point of entry thereinto.

8. The new and improved method of casting relatively large thin walledcup shaped articles composed of aluminum base alloy in a permanent moldcomprising introducing molten, metal into a casting cavity, permittingthe metal to advance in the casting cavity toward remote parts thereof,and maintaining the forward part of the advancing metal in fluidcondition by adding thereto at spaced points highly heated moltenmetalwithdrawn from the casting cavity adjacent to its point of entrythereinto. i

9. A mold for making aluminum alloy castings comprising relativelymovable mold members having their adjacent faces suitably recessed toform a casting cavity for i an enlarged cup shaped article, a gatecavity anda feeder cavity. the ate and feeder cavities communicatingwith the casting cavity at one side thereof, a core supported onthe-mold members and extending into the casting cavity with the innerendand side surfaces spaced apart from the adjacent surfaces of the moldmembers to form a thin walled casting, and a recess formed in one of themold members separate from but communicating with the casting cavity atpoints adjacent to and remote from the feeder cavity.

.on the mold members and extending into the casting cavity with theinner end and side surfaces spaced apart from the adjacent v surfaces ofthe mold members to form a thin walled casting, and a recess formed inone of the mold members separate from but communlcating with the castingcavity at points adjacent to and remote from the feeder cavity, thecrosslsectional dimensions of the said recess being greater than thoseof the casting cavity.

11..A mold for making aluminum alloy castings comprising relativelymovable mold members having their adjacent faces suitably recessed toform a casting cavity for an enlarged cup shaped article, a gate cavity7 The new and improved-method of cast- .and' B3 feeder y, e g and feedercavities communicating with the casting cavity at one side thereof, acore supported 'on the mold members and extending into the castingcavity with the inner end and side surfaces spaced apart from theadjacent surfaces of the mold members to form a thin walled casting, andtwo recesses formed one in each of the 'mold members separate from butcommunicating with the casting. cavity at points adjacent to and remotefrom the feeder cavity.

12. A mold for making aluminum alloy castings comprising relatively'movable mold members having their adjacent faces suitably recessed toform a casting cavity for an enlarged cup shaped article a gate cavityand a feeder cavity the gate and feeder cavities communicating withthecasting cavity at one side thereof, acore supported on the moldmembers and extending mold members having their adjacent faces suitablyrecessed to form a casting cavity for an enlarged cup shaped article, agate cavity and a feeder cavity, the'gate and feeder cavitiescommunicating with the casting cavity at one side thereof, a coresupported on the mold members and extending into the casting cavity withthe inner end,

and side surfaces spaced apart. from the adjacent surfaces of the moldmembers to 3o gate.

5 the feeder cavity and communicating with an enlarged riser recess,

14. A permanent mold for aluminum castings comprising relatively movablemold members suitably recessed in their abutting faces to form anenlarged casting cavity,

and communicatinggate and feeder cavities,

' a core extending into the casting cavity and forming the inner wallsof the casting cavity for a thin walled article, and 'means forwithdrawing molten metal from the casting cavity adjacent to the feederand returning it to the casting cavity at points remote from the feeder.

15. A permanent mold for aluminum 9 castings comprising relativelymovable mold members suitably recessed in their abutting faces .to forman enlarged casting cavity, and communicating gate and feeder cavities,a core extending into the casting cavity and 95 forming the inner wallsof the casting cavity for a thin walled article and means forwithdrawing metal from the top of the casting cavity adjacent to thegate and returning it to the top of the cavity remote from the 16. Apermanent mold for aluminum castings comprising movable mold memberssuitably recessed in their abutting faces to form an enlarged castingcavity, and communicating gate, and feeder cavities, a core extendinginto the casting cavity and forming the inner walls of the castingcavity for a thin walled article and means for withdrawing molten metalfrom the casting cavity adjacent the feeder and returning it to thecasting cavity at points remote from the feeder, said means comprising aseparate passage formed between a side surface of the core and theadjacent surface of the mold members.

17. A permanent mold for aluminum cast in s comprising movable moldmembers suitab y recessed in their abutting faces to form an enlargedcasting cavity, and communicating gate and feeder cavities, a coreextending into the casting cavity and forming the inner walls of thecasting cavity for athin walled article and means for withdrawing.molten metal from the casting cavity adjacent the feeder and returningit to the casting cavity at points remote from the feeder, said meanscomprising a separate passage formed between a side surface of the coreand the adjacent surface of the mold members and riser passagescommunicating with and located above said passage.

18. A mold having two mold members hinged at one side, casting and gaterecesses in abutting faces of mold members, a core to form a thinwalled, cup shaped casting cavity, a horizontally movable mold part inone of the mold" members, a vertically movable core co-operating withthe mold, mem bers, core and mold part to form on the casting a handlecomprising outwardly extending converging arms having their inner 7surfaces diverging downwardly, the said movable core comprising anenlarged lower end and a shank of reduced size offset with respect tothe vertical center line of the said lower end.

19. The new and improved method of casting thin walled, aluminum basealloy articles in a permanent mold comprising feeding molten alloy intothe casting cavity at one side thereof, permitting'the metal to advancein the casting cavity toward remote parts thereof and adding, to theforward part of the advancing metal until the casting cavity iscompletely filled, additional molten metal having a temperature higherthan the said advancing metal at the point of junction of the metals.

20. A permanent mold for aluminum castings comprising relatively movablemold members suitably recessed in their abutting faces to form anenlarged casting cavity, and communicating gate and feeder cavities, acore extending into the casting cavity and forming the inner walls ofthe casting cavity for a thin walled article, and means for withdrawingmolten metal from adjacent to the feeder and leading it into the castingcavity at points remote from the feeder.

In .testimony whereof I hereunto afiix my signature this 18th day ofFebruary, 1924.

ALLEN B. NORTON.

